A driver input gauging is required in order to combine the gradually staggered activation of control elements by the driver with a targeted effect in the clearest possible manner.
An effective metering ability is particularly needed during braking and acceleration, said metering ability resulting in a predictable acceleration and/or deceleration of the motor vehicle. Only this ability to predict the reaction of the motor vehicle makes it possible, using familiarization and learning effects, to create a driving sensation tailored to the respective motor vehicle, said driving sensation giving the driver in question an ability to react which itself enables suitable responses in critical driving situations.
A corresponding gauging was originally effected in that the control elements, in the form of pedals for instance, were directly connected to displaceable function parts by means of mechanical connecting elements. An activation of the control elements thus automatically results in a metered displacement of the associated function part, for instance a flap of a carburetor restricting the air flow. A suitable adjustment ensures that the complete available pedal stroke is available for a precisely metered activation of the control element.
Modern systems for engine timing generally operate without a direct mechanical connection of a control element to a corresponding displaceable function part. The control elements to be activated by the driver should however correspond to conventional systems with regard to their functionality, so that extensive refamiliarization is not required if the type of motor vehicle is changed.
In the case of the accelerator, the position of the pedal is detected by corresponding sensors for this purpose and is translated into a position signal distinctly describing the position of the pedal. At the same time, the value of a parameter of the driver which is relevant for the drive system of the motor vehicle can be derived from the position of the accelerator. A corresponding gauging of this driver input allows a signal derived from the position signal of the accelerator to be achieved, said signal being routed to the motor timing, and resulting in an adjustment of this parameter corresponding to the driver input, provided the required value can be made available.
In particular, with torque-related interpretations of the driver input, two methods have hitherto been established for gauging the torque required by the driver.
The use of a permanently predetermined maximum value of the torque and the compensation of the maximum torque required is known. This maximum requirement exists for instance when the accelerator, as a position-relevant control element, is completely depressed. The respective current value of the torque required by the driver is determined according to this method, in which the fraction of the maximum value of the torque actually required by the driver is derived from the position of the pedal in relation to the full throttle position.
Aside from the respective current driver input, numerous further measurement variables are incorporated into modern motor vehicles in the timing of the torque to be released, which can partially result in a significant reduction in the maximum torque released. A restriction of the torque of this type partially has a higher priority compared with the driver input. When the torque desired by the driver is greater than the maximum possible torque, dead travel or play develops at the accelerator with a gauging with a constant maximum value. Said dead travel or play at least temporarily restricts the possibilities of the driver of exerting an influence on the driving behavior of the driven motor vehicle. This is a significant disadvantage of the method, particularly because some measurement variables, which predominantly result in a reduction in the maximum torque available, are not consciously recognized or not recognized at all by the driver.
Methods of a dynamic gauging of the driver input are thus known. In this way, by considering all measurement variables which could contribute to a restriction in the maximum torque, the respective current maximum recallable torque is determined. This maximum recallable torque is assigned to the maximum requirement by means of the driver. The respective current value of the torque actually required by the driver is likewise determined according to this method, in which the fraction of the maximum value of the torque required by the driver, which is in this case current and dependent on different influential parameters, is derived from the position of the pedal in relation to the full throttle position. A dead travel at the accelerator is prevented in this way. The disadvantage of this method is thus that an absolute calibration of the driver input is no longer possible. The driver input can be distorted by the engine dynamics, which is influenced by the most diverse boundary conditions such as for instance a smoke intensity restriction function. Numerous influential parameters partially change the gauging in short time segments, whereby the pick-up behavior of the engine changes constantly in terms of the driver's perception. As these changes can only be predicted in part, they have a negative effect, under some circumstances, on the development of the already claimed driving sensation, which can impair the safety in critical driving situations. This disadvantage can only be incompletely compensated by means of automatic control and safety systems.
The described problems can basically also be attributed to gauging systems, which are not based on or not only based on a torque-related interpretation of the driver input.